By utilizing a communication device onboard a moving object such as a vehicle, direct communication between the moving object and various target objects is realized. Communication between a communication device onboard a moving object and various other communication devices is called vehicle-to-X (V2X) communication. For V2X communication, communication systems utilizing dedicated short range communications (DSRC) have been investigated thus far, but recently, investigation into communication systems utilizing mobile phone communication standards such as Long Term Evolution (LTE) is progressing.
Before discussion of V2X communication became active, communication between communication devices, called device to device (D2D), was being investigated. Such D2D communication is disclosed in PTL1, for example.